Is Coral hard enough for everyday rings?

Not ideally. At a Mohs hardness of 3–4, Coral is soft enough to scratch with everyday wear, so it is better suited to earrings, pendants, or occasional-wear rings with protective settings.

How can I tell Coral from dyed bone?

Coral and dyed bone can look alike to the naked eye, but they differ in measurable properties — refractive index (1.486–1.658 for Coral), specific gravity (2.6–2.7), and hardness (Mohs 3–4). A gemologist confirms the distinction with a refractometer and loupe; the Jewelry Identifier app gives a fast first read from a photo.

Does Coral come in colors other than red?

Yes. Coral occurs in red, pink (angelskin), white, black. Color is driven by trace elements and treatment history, and it is one of the biggest factors in a stone's value.

* coral gemstone

Coral: identification, value, and how to spot a fake

Organic gem from marine coral polyps. Mediterranean and Japanese Akamomo (red) and Sardegna are historic sources. CITES-regulated due to endangered species. Soft (Mohs 3-4) — requires gentle handling.

Published May 30, 2026

Quick facts

Mineral family: coral
Chemical formula: CaCO3 (calcite) + organic
Mohs hardness: 3–4
Refractive index: 1.486–1.658
Specific gravity: 2.6–2.7
Crystal system: n/a (organic)
Luster: dull to vitreous

Colors

Coral is found in red, pink (angelskin), white, black. The body color, its saturation, and how evenly it spreads through the stone are among the strongest drivers of value.

How to tell real from imitation

No single test settles it, but a few grounded checks quickly narrow things down for Coral. Hardness, brilliance, and the list of stones it is commonly confused with all give you something concrete to look for.

Scratch resistance: genuine Coral sits at Mohs 3–4, so it should resist scratching from softer materials — a stone that mars far too easily is suspect.
Brilliance & luster: Coral shows a dull to vitreous luster and a refractive index of 1.486–1.658; imitations often look glassier or flatter under the same light.
Density: a real Coral has a specific gravity near 2.6–2.7, so it feels heavier or lighter in the hand than many look-alikes of the same size.
Commonly imitated by: dyed bone, plastic. If a deal looks too good, suspect one of these substitutes first.
Fast first read: photograph the stone in the Jewelry Identifier app to estimate the gemstone and its likely value range, then confirm anything important with a gemological lab.

Common treatments

Treatments are routine for many Coral stones, but they materially affect value and should always be disclosed — an untreated, lab-certified stone commands a clear premium over a treated one.

What to know about Coral

Sources

Wikidata Q11427

* Frequently asked

FAQ

Q. Is Coral hard enough for everyday rings?: A. Not ideally. At a Mohs hardness of 3–4, Coral is soft enough to scratch with everyday wear, so it is better suited to earrings, pendants, or occasional-wear rings with protective settings.
Q. How can I tell Coral from dyed bone?: A. Coral and dyed bone can look alike to the naked eye, but they differ in measurable properties — refractive index (1.486–1.658 for Coral), specific gravity (2.6–2.7), and hardness (Mohs 3–4). A gemologist confirms the distinction with a refractometer and loupe; the Jewelry Identifier app gives a fast first read from a photo.
Q. Does Coral come in colors other than red?: A. Yes. Coral occurs in red, pink (angelskin), white, black. Color is driven by trace elements and treatment history, and it is one of the biggest factors in a stone's value.

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